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A073488
Squarefree numbers having exactly two prime gaps.
7
110, 130, 170, 182, 190, 230, 238, 266, 273, 290, 310, 322, 357, 370, 374, 399, 406, 410, 418, 430, 434, 470, 483, 494, 506, 518, 530, 546, 561, 574, 590, 598, 602, 609, 610, 627, 638, 651, 658, 670, 682, 710, 714, 730, 741, 742, 754, 759, 777, 782, 790
OFFSET
1,1
LINKS
FORMULA
A073484(a(n)) = 2.
EXAMPLE
1430 is a term, as 1430 = 2*5*11*13 with two gaps: between 2 and 5 and between 5 and 11.
MATHEMATICA
q[n_] := SequenceCount[FactorInteger[n][[;; , 1]], {p1_, p2_} /; p2 != NextPrime[p1], Overlaps -> True] == 2; Select[Range[800], SquareFreeQ[#] && q[#] &] (* Amiram Eldar, Apr 10 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Aug 03 2002
STATUS
approved